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[英]Taking all letters from a string converting into lowercase and then arranging them all in alphabetical order
[英]Arranging by Alphabetical Order
我是Java的新手,正在嘗試按字母順序排列術語的arrayList。 (術語定義為字符和整數)(例如{Term('Z',4),Term('C',3),Term('Q',2) ...} )
我的代碼如下:
public Term nextElement()
{
Term max = terms.get(0);
char maxtest = max.getElement();
for (int i = 1; i < terms.size(); i++){
Term tester = terms.get(i);
char maxtest2 = tester.getElement();
if (maxtest2 > maxtest) {
tester = max;
}
}
return max;
}
為什么這不起作用? 以及我該如何完成呢? 我的arrayList稱為用Term類型填充的term
您在這行代碼中遇到的問題。 您的類不是可Comparable
的類型,因此,在哪個屬性或條件上compareTo()
方法將compare
這兩個對象?
res = maxtest.compareTo(maxtest2); //Your maxtest object is not Comparable Type.
您必須使您的類Term
Comparable類型。 和根據您的需要重寫compareTo()
方法。
您沒有提到Term
類的變量或結構。 因此,我假設您的班級有這種Structure。
public class Term implements Comparable<Term> {
private Character alpha;
private int number;
//getter and setters +Constructors as you specified
....
....
...
.....
// Now Set a criteria to sort is the Alphanumeric.
@Override
public int compareTo(Term prm_obj) {
if (prm_obj.getAlpha() > this.alpha) {
return 1;
} else if (prm_obj.getAlpha() < this.alpha) {
return -1;
} else {
return 0;
}
}
現在,您的班級成為可comparable
類型。 因此,您可以應用Collections.sort(Collection obj)
,它會自動sort
ArrayList<Term>
sort
。
在這里,我為此編寫了一個演示。
public static void main(String... args){
List<Term> obj_listTerm = new ArrayList<>();
//add all the data you given in question
obj_listTerm .add(new Term('Z', 4));
obj_listTerm .add(new Term('Q', 2));
obj_listTerm .add(new Term('c', 3));
// print without Sorting your Term ArrayList.
System.out.println("This is the list unsorted: " + myTermList);
// Sort Using Collections.sort() Method.
Collections.sort(myTermList);
// After applying sort() you may see your Sorted ArrayList.
System.out.println("This is the list SORTED: " + myTermList);
}
您可以使用Collection類並對您擁有的術語列表進行排序,只需使Term類具有可比性
public class Term implements Comparable<Term> {
.....
// .....
// criteria to sort is the char
@Override
public int compareTo(Term o) {
if (o.getLetter()> this.letter) {
return 1;
} else if (o.getLetter() < this.letter) {
return -1;
} else {
return 0;
}
}
public static void main(String[] args) {
// test
List<Term> myTermList = new ArrayList<>();
myTermList.add(new Term('Z', 4));
myTermList.add(new Term('Q', 2));
myTermList.add(new Term('c', 3));
// check how the look like
System.out.println("This is the list unsorted: " + myTermList);
// now sort them
Collections.sort(myTermList);
// check how the look like
System.out.println("This is the list SORTED: " + myTermList);
}
如果您不想實現可比性,則修改此:
res = maxtest.compareTo(maxtest2);
因為maxtest和maxtest2是基元而不是對象,所以這是無效的...
用代替
res = Character.compare(maxtest, maxtest2);
然后使用結果驗證您的邏輯並做出決定:
if (res >1) {
System.out.println("bigger");
}else if (res<1) {
System.out.println("smaller");
}else {
System.out.println("same");
}
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